1) Field of the Invention
The present invention relates to a stent device and, in particular, to a stent removal and repositioning device that is capable of removing a stent from a lumen or repositioning the stent within the lumen.
2) Description of Related Art
Stents are devices that are inserted into body lumens such as vessels or passages to keep the lumen open and prevent closure due to a stricture, external compression, or internal obstruction. In particular, stents are commonly used to keep blood vessels open in the coronary arteries, and they are frequently inserted into the ureters to maintain drainage from the kidneys, the bile duct for pancreatic cancer or cholangiocarcinoma, or the esophagus for strictures or cancer. Vascular as well as nonvascular stenting has evolved significantly; unfortunately, there remain significant limitations with respect to the technology for positioning and removing stents following implantation into various portions of a patient's anatomy.
In various areas of application, e.g., bronchus, biliary, trachea, or esophagus, the stents must be removable from the body or repositionable as a function of the course of the disease or treatment. This can be problematic since newly formed tissue can grow on the support frame of the stent and even grow through it, which can result in complications when removing a stent. In this regard, stents have been developed that include a support frame surrounded on the outside by a thread or wire. The support frame can be radially constricted by pulling on the thread ends that are each provided with a loop or the like, creating a “purse-string” effect, which makes it possible for the frame to be removed. However, when the wire or thread is guided or braided in multiple windings around the support frame, a high degree of friction results between the two stent components, which has a disadvantageous effect on the explantation process. In addition, stents having eyelets for looping the thread therethrough may have sharp edges that cause the thread to tear or break during the removal process.
Alternatively, surgeons have grasped the stent with forceps or a similar instrument to reposition or remove the stent from within the lumen. However, this can be complex at times. For instance, grasping the stent risks damage to the stent and/or the surrounding tissue, e.g., during removal of a tracheal stent with grasping forceps, the vocal chords may be damaged if the stent is in its deployed state with an expanded diameter. Also, grasping may lead to damage to the stent itself, as the forceps may have difficulty accessing or adequately gripping the stent to remove or reposition it.
Thus, there is a need in the industry for a stent removal device that reduces the risk of damage to the stent, thread or suture, and the surrounding tissue. In addition, there is a need for a stent removal device that is capable of easily accessing the stent, as well as effectively constricting the stent and thereafter repositioning and/or removing the stent from a lumen.